1. Field of the Invention
This invention relates in general to a system for receiving digital communication signals which are modulated on a carrier in the form of binary frequency modulation in a reflection affected propagation medium and in particular for a reception at mobile stations on long distance connections and scattered beam connections.
2. Description of the Prior Art
In digital communication transmission systems under heavily disrupted propagation conditions (multi-path propagation) the range is approximately inversely proportional to the bit rate to be transmitted. The limiting case determining the range is represented by the total signal extinction which as a consequence of the different transit times (propagation times) is caused by the indirect propagation path. The differential time delay of the reflected wave and the direct path amount at the reception point to 180.degree. out of phase and therefore the waves mutually cancel each other. In a wide range before this limiting case occurs information losses occur as a result of the delay time distortion and amplitude distortion which give rise to very high error rates in data transmission.